(1) Field of the Invention
The present invention relates to damping support structures for preventing vibrations of manufacturing apparatus. Such a support structure is installed in an LSI manufacturing plant, a laser appliance manufacturing plant or the like to support apparatus for manufacturing ultra-high precision devices such as semiconductors and printed circuit boards. The support structure absorbs vibrations due to earthquakes or microvibrations due to running vehicles through a floor or other base structure, thereby preventing vibrations of a table supporting the manufacturing apparatus.
(2) Description of the Prior Art
At the LSI manufacturing plant, laser appliance manufacturing plant and the like, it is necessary to suppress microvibrations since even microvibrations result in defective products. A conventional damping support structure includes spring elements such as laminated rubber layers and air springs arranged between a table on which a manufacturing apparatus is mounted and the floor or other base structure. These spring elements elastically support the apparatus table, and efficiently absorb microvibrations while mitigating shocks due to vibrations.
This conventional support structure, however, is incapable of eliminating the vibrations although it can mitigate the vibrations transmitted to the apparatus table.
There is another type of support structure which includes an auxiliary mass and a damper such as a hydraulic cylinder for preventing vibrations of the apparatus table. This structure has the disadvantage that the apparatus table becomes large and heavy with the inclusion of the auxiliary mass and damper. This structure must also has a sufficient strength for elastically supporting the auxiliary mass and damper.
Further, the damper has a damping force adjustable by the viscosity of oil, and the viscosity is too high for damping microvibrations. This impairs the vibration-proofing performance of the apparatus table.